If you want a good dealer to obtain lots of bits from, then ebuyer, overclockers, and Toms hardware are well worth checking out (Toms for tech info).
I managed to get the following spec for £735.00!!!! ( $1315.65!!!!!)
AMB Athlon (Venice) 3500 64bit Processor £180.00 (ebuyer)
1024MB Cosair 400DDR RAM £57.00 (ebay)
200GB Western Digital H/D , with 8MB Cache £59.00 (ebuyer)
256MB Nvidia Geforce 6800GT £199.00(overclockers)
LG 16X DVD ROM £15.00 (ebuyer)
LG 16x DVD RW £31.00 (ebuyer)
Abit AV8 '3rd eye' M/B £69.00 (ebuyer)
Thermaltake VA3000 Dream Tsunmai case £75.00 (micro-direct)
Q-Tec Twin Fan 550W Gold PSU £25.00 (ebay)
Labtec 485 2.1 Sub and Spkrs (1000W MPO) £25.00 (ebuyer)
All running of off 64bit Windows XP PRO
I have another 1024MB of DDR400 RAM, along with a 24 bit creative sound card, which has been put int the machine too, but the total cost of this was £735.00!! or $1315.65.
I spent months looking around for a decent set up and these were the best prices I've seen on the net.
Let me know how you get on!